MACKIE MDB-2P - Passive stereo DI box for keyboards and synthesizers

MACKIE MDB-2P – Passive stereo DI box for keyboards and synthesizers

The Mackie MDB-2P Stereo Passive DI is the ideal passive solution for converting high-impedance signals from stereo instruments (keyboards, synthesizers, media players) into two balanced, low-impedance outputs without the need for power. It features two high-impedance 1/4" inputs with parallel thru outputs and –15 dB pads for protection against high-level signals. Its low-impedance XLR outputs include ground lift switches to eliminate ground loops, delivering clean, distortion-free audio even in demanding environments.

Main features

• Inputs: 2 × 1/4″ TS high impedance jack (140 kΩ) with parallel Thru outputs.
• Pad: –15 dB for each input, ensuring distortion-free performance with high-level signals.
• DI Outputs: 2 × balanced XLR (400 Ω) with Ground Lift to eliminate ground hum.
• Frequency response: 20 Hz – 20 kHz ±0.2 dB.
• Dynamic range: 128 dB.
• Total harmonic distortion: 0.002% @ 1 kHz.
• Output impedance: 400 Ω unbalanced.
• Construction: Heavy-duty “Built-Like-A-Tank™” metal chassis.
• Dimensions: 1.5″ × 3.4″ × 5.8″ (38 × 86 × 147 mm).
• Weight: 0.8 lb (0.36 kg).

User benefits

• Perfect adaptation: Passive transformation of high-level signals to balanced lines without noise or distortion.
• Signal Protection: –15 dB pads and Thru outputs prevent overloads and maintain connection to amplifiers.
• Noise Elimination: Ground Lift on each channel to suppress hum caused by ground loops.
• Ease of use: No power required; just plug and play.
• Touring Durability: Rugged design suitable for touring, studios and live sound rooms.

Use cases

• Injection of stereo outputs from keyboards and synthesizers to consoles or microphone preamps.
• Connecting media players and backing tracks to PA systems.
• Recordings and live performances requiring a balanced signal without external power supply.
• Fixed installations in auditoriums, churches and conference rooms.

Frequently Asked Questions

• Does it require power? No; it's passive and doesn't require batteries or phantom power.
• Can I also connect amplifiers? Yes; the Thru outputs allow you to maintain the signal to amplifiers or pedals.
• How do I avoid hum? Activate Ground Lift on the XLR output to eliminate ground loops.
• Which pad is best for my keyboard? The –15 dB pad is ideal for keyboards with high line-level outputs.

Description for projects

Mackie MDB-2P DI Box: 2 x 1/4″ TS (140 kΩ) inputs with –15 dB pad and Thru, 2 x balanced XLR (400 Ω) outputs with Ground Lift, 20 Hz–20 kHz, THD 0.002%, metal chassis, 38×86×147 mm, 0.8 lb.